Zinc-deficient diet impairs adaptive changes in the remaining intestine after massive small bowel resection in the rat

Modulation of maltose preference by selection from dextrin, maltose and glucose diets in zinc-deficient rats

This study examined whether the chain length of glucose in the diet could affect the selection of foods by Zn-adequate and Zn-deficient rats. Dextrin, maltose and glucose were used as sources of carbohydrate in the diet and the selection patterns of the rats were analyzed for 28 d by a 3-choice selection. Diets provided as a set of three either Zn-adequate or Zn-deficient diets were rotated daily. The Zn-adequate control rats selected widely from the three diets throughout the 28 d. In contrast, rats fed a Zn-deficient diet selected exclusively and continuously the dextrin diet or dextrin and glucose diets from the three diets over the experimental periods. The average daily total food intakes of rats fed a Zn-deficient diet were very significantly decreased. The selections of dextrin, maltose and glucose diets in the 3-choice methods of the control rats were 5.7+/-1.6(b), 5.8+/-2.0(b) and 2.7+/-0.9(a) g/d, respectively (p<0.05), and those of the Zn-deficient rats were 6.4+/-2.5(c), 0.8+/-1.3(a) and 2.6+/-1.4(b) g/d, respectively (p<0.05). The ratios of the selected maltose-diet in the Zn-adequate control and the Zn-deficient rats were 40.8+/-13.8 and 9.0+/-15.6%, respectively (p<0.01) and those of the dextrin-diet were 40.3+/-11.4 and 63.0+/-22.3%, respectively (p<0.05). The decreased preference for the maltose-diet in the Zn-deficient rats may reflect the increased selection of the dextrin-diet.

Influence of dietary zinc and copper on digestive enzyme activity and intestinal morphology in weaned pigs1

The current study was conducted to investigate the effects of high dietary concentrations of Zn as zinc oxide and Cu as copper sulfate on the activity of digestive enzymes in the pancreas and the intestinal mucosa, intestinal morphology, and mucin histochemistry in pigs after weaning. Thirty-two pigs were weaned at 4 wk of age. The pigs were fed standard weaning diets supplemented with Zn (100 or 2,500 ppm) and Cu (0 or 175 ppm) in a 2 x 2 factorial arrangement of treatments for a 14-d period. In pancreatic tissue, the activity of amylase, carboxypeptidase A, chymotrypsin, trypsin, and lipase increased (P < 0.01) in pigs fed 2,500 ppm of Zn, whereas the activity of carboxypeptidase B and carboxylester hydrolase was unaffected. Copper had no effect on the activity of pancreatic enzymes. In small intestinal contents, the total activity of amylase and carboxypeptidase A was greater in pigs fed 100 ppm of Zn (P < 0.05), whereas feeding 2,500 ppm of Zn increased the chymotrypsin activity (P < 0.001). The remaining enzymes were unaffected by dietary Zn concentration. The villi were longer in the cranial small intestine (P < 0.001) in pigs fed 100 ppm of Zn than in pigs fed 2,500 ppm of Zn, but otherwise there were no clear effects of Zn and Cu supplementation on intestinal morphology. In the cranial small intestine, the activity of maltase (P < 0.001), sucrase (P < 0.001), and lactase was greater in pigs fed 100 ppm of Zn, even though there was a Zn x Cu interaction (P < 0.05) in lactase activity. In the middle and caudal small intestine, no clear differences between dietary treatments were observed. The activity of gamma-glutamyl transpeptidase in the intestinal mucosa was not affected by dietary Zn or Cu. In pigs fed 100 ppm of Zn, the activity of aminopeptidase N was greater in the caudal small intestine, but dietary Zn or Cu had no effect on aminopeptidase N in the cranial and middle small intestine. No effect of dietary Zn or Cu supplementation was found on carbohydrate histochemistry in the caudal small intestine, whereas high dietary Zn increased the area of neutral, acidic, and sulfomucins in the cecum (P < 0.01) and in the colon (P < 0.001). In summary, high dietary Zn increased the activity of several enzymes in the pancreatic tissue and increased the mucin staining area in the large intestine, whereas Cu had no clear effect on these variables. However, no definite answers were found as to how the growth promoting and diarrhea reducing effects of excess dietary Zn are exerted.

Intestinal permeability in adult patients with growth hormone deficiency

Pathological disruption of the intestinal mucosa increases the paracellular pathway, leading to an increase in the penetration of large molecules. Since growth hormone (GH) has a trophic intestinal effect, we used a double marker test to enable examination of intestinal permeability, which reflects the state of integrity of the intestinal mucosa. We recruited 22 adult patients, mean age 54+/-13.3 years, with GH deficiency due to partial or total hypopituitarism. None had received GH treatment at any time, although they were all in optimized replacement therapy. A control group was composed of 19 healthy age-matched relatives. The intestinal permeability test was performed with lactulose (5 g) and mannitol (1 g) after an oral load of 100 ml of aqueous solution. The urinary lactulose/mannitol ratio and the percentages of lactulose and mannitol excreted were determined on a 5-h urine collection. There were no significant differences between the patients and the control group in the lactulose/mannitol ratio (0.087+/-0.059 vs 0.077+/-0.064, respectively) or in the urinary excretion percentages of lactulose (0.067+/-0.048% vs 0.073+/-0.070%, respectively) or mannitol (5.127+/-3.269% vs 5.068+/-2.985%, respectively). In conclusion, no increase in intestinal permeability was detected in patients with GH deficiency, so that in spite of the known trophic effects of GH on the epithelial crypt cells, there was no intestinal hyperpermeability in these patients.

Zinc, Copper, and Metallothionein Metabolism after Jejunoileal Bypass Surgery or Small Bowel Resection in Rats

Liver dysfunction is a frequent complication of jejunoileal bypass (JIB) surgery, a procedure commonly used until recently to treat morbid obesity. It has been suggested that liver failure in JIB patients is due to bacterial overgrowth and translocation from the bypassed intestine. Because invading microorganisms cause hepatic inflammation these experiments evaluated zinc, copper, and metallothionein (MT) in two experimental rat models of intestinal surgery to determine whether their distribution in plasma and tissues was similar to the highly characteristic pattern observed during an inflammatory response. In the JIB rat model 90 per cent of the small intestine was isolated from the flow of digesta but remained viable in the abdominal cavity. In the small bowel resection (SBR) model 90 per cent of the small intestine was removed and the remaining intestine was resected. Data collected 21 days after surgery showed decreased growth rate and plasma zinc in the SBR and JIB rats that was significantly improved by supplemental zinc. All other measures of zinc, copper, and MT metabolism in the SBR rats were similar to those of controls. In JIB rats, however, liver copper, MT protein, and MT mRNA were significantly elevated, and a high proportion of the intracellular zinc and copper was associated with MT. The pattern of zinc, copper, and MT distribution in systemic circulation and liver of JIB rats suggests hepatic inflammation superimposed on low zinc and copper status. Lack of a similar response in the SBR rats confirms the involvement of the bypassed intestinal segment and supports the hypothesis that bacterial overgrowth and translocation are responsible for liver inflammation and dysfunction in JIB patients.

Interactions between nutrients and peptide growth factors in intestinal growth, repair, and function

Several lines of evidence demonstrate that general nutritional status, specific nutrients (eg, zinc, glutamine), and certain trophic growth factors (eg, growth hormone, insulin-like growth factor I, keratinocyte growth factor, and glucagon-like peptide-2) have important interactions relevant for intestinal growth and function. Adequate nutritional status is critical for endogenous growth factor synthesis in the gut and other tissues and is an important mediator of organ responsiveness to exogenous growth factor administration. Both endogenously synthesized and exogenously administered growth factors upregulate nutrient uptake and utilization by gut mucosa, skeletal muscle, and other organs. Emerging data from both animal and human studies indicate that combinations of selected growth factors and specific nutrients may improve the growth, adaptation, and repair of the intestinal mucosa. Additional studies to determine basic mechanisms of nutrient-growth factor interactions and the safety and efficacy of treatment with combinations of specific nutrients and recombinant growth factors are needed. Results of these investigations should define new methods for support of the intestinal tract during short bowel syndrome (SBS), catabolic illness, and malnutrition.